plot.imp {irtoys}

A plot method for the interaction model

Description

Plot the item-total regressions fit by the interaction (or Rasch) model

Usage

## S3 method for class 'imp'
plot(
  x,
  items = NULL,
  shade = 10,
  highlight = -Inf,
  add = FALSE,
  main = "Item-total regression",
  label = FALSE,
  ...
)

Arguments

x

An object produced by function interactionModel

items

The items to plot (column numbers). If NULL, all items will be plotted

shade

The part of the probability mass for the sum scores to shade out, shown as percentage. Default is 10: shade the most extreme 10 Ignored when add=TRUE.

highlight

Cutpoint for the interaction parameter below which a regression line will be highlighted in red. Default is -Inf (do not highlight).

add

When add=TRUE, the graph is added to a plot, otherwise a new plot is started. Default is FALSE.

main

The main title of the plot, given that add=FALSE.

label

When label=TRUE, individual curves will be labeled with the item number.

...

Any additional plotting parameters

Author(s)

Ivailo Partchev, using theory and C code by Gunter Maris

See Also

interactionModel

Examples

plot(interactionModel(Scored), highlight=-.3)